A blowout preventer assembly is employed for offshore well drilling operations. The blowout preventer assembly includes a blowout preventer stack (BOP stack) that includes several ram preventers. The BOP stank lands on and corrects to a wellhead housing at the sea floor. A lower marine riser package (LMRP) connects to a tubular mandrel on the upper end of the BOP stack. The LMRP secures to a lower end of the riser and has control pods that control various functions of the BOP stack and LMRP. The LMRP also has one or more annular blowout preventers, which can seal around pipe of a variety of sizes as well as completely close the passage.
The LMRP has a connector that is hydraulically actuated and will releasably connect the LMRP to the mandrel of the BOP stack. The annular BOP is located directly above the LMRP and connected by an external bolted flange.
The LMRP and BOP stack are large pieces of equipment, quite tall. It would be desirable to reduce the overall height of the BOP assembly because of height restrictions when the equipment is stowed on the rig. A reduced height LMRP would allow the use of the equipment on rigs with a lower deck height. A reduced height LMRP would allow for smaller rig designs. It would also allow for the installation of an additional ram BOP preventer in the BOP stack without adding the full height of the additional ram to the assembled BOP stack and LMRP. A reduced height LMRP would also allow replacement of shorter height annular BOPs, if desired, for taller height annular BOPs.